Skip to content
A dependency free utility for cropping images based on a focus point ~2.13kB gzipped
TypeScript HTML JavaScript
Branch: master
Clone or download
Latest commit 04b8373 Oct 5, 2019
Permalink
Type Name Latest commit message Commit time
Failed to load latest commit information.
src Test number not string Oct 5, 2019
test Add FocusedImage test file Nov 11, 2017
tools
.editorconfig Restructure project for packaging Nov 5, 2017
.gitignore
.prettierrc Restructure project for packaging Nov 5, 2017
.travis.yml Restructure project for packaging Nov 5, 2017
LICENSE Initial commit Oct 31, 2017
README.md Add gif and emoji to readme Feb 10, 2018
image-focus-demo.gif Add demo gif Feb 10, 2018
package-lock.json
package.json 1.1.0 Oct 5, 2019
rollup.config.ts Minify and increment version Nov 7, 2017
tsconfig.json
tslint.json Restructure project for packaging Nov 5, 2017
webpack.config.js

README.md

image-focus 📷

A dependency free utility for cropping images based on a focus point ~2.13kB gzipped

npm version npm downloads MIT

Demo

Demo

Check out the demo and then play with editing it

Docs

Docs generated by typedoc

Usage

Focus Coordinates range between -1 and 1 for both x and y axes. The FocusPicker class will help enable users to select the focus point to be used with an image.

FocusedImage

There are two ways to supply the coordinates when initializing the FocusedImage class

Data Tags

<div class="focused-image-container">
  <img class="focused-image" src="https://picsum.photos/2400/1400" data-focus-x="0.34" data-focus-y="-0.21">
</div>
import { FocusedImage } from "image-focus"

const img = document.querySelector('.focused-image') as HTMLImageElement
const focusedImage = new FocusedImage(img)

Using focus Option

<div class="focused-image-container">
  <img class="focused-image" src="https://picsum.photos/2400/1400">
</div>
import { FocusedImage } from "image-focus"

const img = document.querySelector('.focused-image') as HTMLImageElement
const focusedImage = new FocusedImage(img, {
  focus: {
    x: 0.34,
    y: -0.21
  }
})

FocusPicker

Provide an onChange callback that will receive a Focus object that has x and y properties for the newly selected coordinates. Optionally supply a focus to initialize with, or a retina src to use instead of the default white ring SVG.

import {FocusedImage, FocusPicker} from "image-focus"

const imgEl = document.getElementById("focused-image") as HTMLImageElement
const focusedImage = new FocusedImage(imgEl)

const focusPickerEl = document.getElementById("focus-picker-img") as HTMLImageElement
const focusPicker = new FocusPicker(focusPickerEl, {
  onChange: focus => focusedImage.setFocus(focus),
  focus: startingFocus,
})

What's going on?

The <img/> element is being set to position: absolute; and having its top and left properties adjusted based on some calculations using the image and parent containers' aspect ratios and dimensions. The <img/>'s parent container gets set to position: relative; and overflow: hidden; to create the effect. There are a few other inline styles that get applied, so if anything appears to be behaving unexpectedly, be sure to check that the inline styles on both the <img/> and its parent aren't being overridden by CSS on your page (especially from rules using !important).

Additionally, because the FocusedImage is positioned absolutely so it can shift as needed, its container needs to manage its own height and width. If you aren't seeing an image appear at all, it is likely that the parent div's height is fully collapsed.

What if I'm not using npm and a build process?

That's okay! unpkg has you covered. Just add this script tag to your page and the image-focus module is exposed in the global namespace under window.imageFocus.

<script src="https://unpkg.com/image-focus@1.0.2"></script>

Then in some script that loads after the above script tag:

var imgEl = document.querySelector('img.focused-image');
var focusedImage = new imageFocus.FocusedImage(imgEl, {x: 0.25, y: -0.3});

Attributions

This project was largely inspired by and adapted from jquery-focuspoint by jonom and used typescript-library-starter to scaffold the build process.

You can’t perform that action at this time.